Conventionally, in a small electronic device such as a portable telephone, it has been carried into practice that a plurality of circuit elements constituting, the device are integrated in one-chip laminated ceramic component and the laminated ceramic component is mounted on a main substrate (Patent Document 1, for example).
FIG. 11 illustrates a laminate structure of a laminated ceramic component 1, in which a plurality of ceramic layers 2 are laminated to constitute a laminated ceramic substrate 20. Formed on each surface of the ceramic layers 2 are a plurality of circuit element patterns 3 constituting an inductor or a capacitor. These circuit element patterns 3 are connected to each other by a vertical conduction path (hereinafter referred to as a via hole) 31 formed by penetrating the ceramic layers 2. A side electrode 47 is provided on a side surface of the laminated ceramic substrate 20 and connected to the circuit element patterns 3.
A cavity 21 is provided on a surface of the laminated ceramic substrate 20. An electronic component 4 such as a surface acoustic wave filter is mounted on a bottom surface of the cavity 21. The electronic component 4 is connected to the circuit element patterns 3 through a bonding wire 32.
A lid 5 covering the cavity 21 is placed on the surface of the laminated ceramic substrate 20 to constitute the laminated ceramic component 1 packaged.
The above-described laminated ceramic substrate 20 is manufactured by the steps shown in FIG. 10.
First, as shown in FIG. 10(a), a green sheet 25 including a ceramic mixed material is prepared. Next, as shown in FIG. 10(b), a through hole 22 for a cavity, a through hole for a via hole (not shown), and a circular-shaped through hole 23 for a side electrode are provided at desired locations of the green sheet 25. Thereafter, as shown in FIG. 10(c), the through hole for a via hole and the through hole 23 for a side electrode are filled with a conductive material 24. Subsequently, as shown in FIG. 10(d), the conductive material 24 is printed on a surface of the green sheet 25 to form a circuit element pattern 30.
Green sheets 25 thus obtained are laminated and thereafter integrated by heat press or other methods to prepare a green-sheet laminated body 26 shown in FIG. 10(e).
Thereafter, as shown in FIG. 10(f), the green-sheet laminated body 26 is divided for each cavity 21 to obtain a plurality of green-sheet laminated body chips 27. Then, as shown in FIG. 10(g), each of the green-sheet laminated body chips 27 is fired to obtain the laminated ceramic substrate 20.
As shown in FIG. 11, the electronic component 4 is mounted on the bottom surface of the cavity 21 of the laminated ceramic substrate 20 thus obtained. Then wire bonding is applied thereto and the lid 5 is placed to thereby complete the laminated ceramic component 1.
[Patent Document 1] U.S. Pat. No. 3,336,913, FIG. 6(b)
A conventional laminated ceramic substrate includes a semicircular side electrode in which a side edge electrode layer formed on a side edge portion of a ceramic layer overlaps with and connects to a side edge electrode layer formed on a side edge portion of another ceramic layer directly above and/or directly below the former ceramic layer. This can be obtained because a circular-shaped through hole for a side electrode is filled with a conductive material and thereafter divided. FIG. 4(a) is a partial top view in the vicinity of a circular-shaped through hole 23 for a side electrode of a conventional green-sheet laminated body 26. Through holes 23a, 23b, and 23c for a side electrode each have the same shape. For example, a green sheet 25a is disposed on a designed center in a side-electrode width direction and on a designed center in a side-electrode depth direction with a green sheet 25b laminated thereon shifted from the designed center in the side-electrode width direction to the left in the drawing by X1 greater than the radius of the through hole for a side electrode and a green sheet 25c further laminated thereon shifted from the designed center in the side-electrode width direction to the right in the drawing by X2 greater than the radius of the through hole for a side electrode. The green sheets 25b and 25c are both disposed on the designed center in the side-electrode depth direction. A width direction center of the through hole 23a for a side electrode of the green sheet 25a is the same as the designed center 43 in the side-electrode width direction. In contrast, a width direction center 42b of the through hole 23b for a side electrode of the green sheet 25b is shifted from the designed center 43 in the side-electrode width direction to the left in the drawing by the shift amount X1. A width direction center 42c of the through hole 23c for a side electrode of the green sheet 25c is also shifted from the designed center 43 in the side-electrode width direction to the right in the drawing by the shift amount X2.
FIG. 4(b) is a partial side view in the vicinity of a side electrode of a green-sheet laminated body chip 27 obtained by dividing the green-sheet laminated body 26 along a line 45a-45a (same as the designed center 45 in the side-electrode depth direction). As seen in the drawing, side edge electrode layers 41a, 41b, and 41c that must essentially be electrically connected are disconnected at a border between the neighboring side edge electrode layers 41b and 41c of the green sheets 25b and 25c, respectively, resulting in a laminated ceramic substrate with a disconnection defect.
FIG. 6(a) is a partial top view in the vicinity of a circular-shaped through hole 23 for a side electrode of a conventional green-sheet laminated body 26. Through holes 23d, 23e, and 23f for a side electrode each have the same shape. For example, a green sheet 25d is disposed on a designed center in a side-electrode width direction and on a designed center in a side-electrode depth direction with a green sheet 25e laminated thereon shifted from the designed center in the side-electrode depth direction to the bottom in the drawing by Y3 smaller than the radius of the through hole for a side electrode and shifted from the designed center in the side-electrode width direction to the left in the drawing by X3 smaller than the radius of the through hole for a side electrode, and with a green sheet 25f further laminated thereon shifted from the designed center in the side-electrode depth direction to the top in the drawing by Y4 smaller than the radius of the through hole for a side electrode and shifted from the designed center in the side-electrode width direction to the right in the drawing by X4 smaller than the radius of the through hole for a side electrode. A depth direction center and a width direction center of the through hole 23d for a side electrode of the green sheet 25d are the same as the designed center 45 in the side-electrode depth direction and the designed center 43 in the side-electrode width direction, respectively. In contrast, a depth direction center 44e of the through hole 23e for a side electrode of the green sheet 25e is shifted from the designed center 45 in the side-electrode depth direction to the bottom in the drawing by the shift amount Y3 and a width direction center 42e of the through hole 23e for a side electrode of the green sheet 25e is shifted from the designed center 43 in the side-electrode width direction to the left in the drawing by the shift amount X3. A depth direction center 44f of the through hole 23f for a side electrode of the green sheet 25f is also shifted from the designed center 45 in the side-electrode depth direction to the top in the drawing by the shift amount Y4 and a width direction center 42f of the through hole 23f for a side electrode of the green sheet 25f is also shifted from the designed center 43 in the side-electrode width direction to the right in the drawing by the shift amount X4.
FIG. 6(b) is a partial side view in the vicinity of a side electrode of a green-sheet laminated body chip 27 obtained by dividing the green-sheet laminated body 26 along a line 45b-45b (same as the designed center 45 in the side-electrode depth direction). As seen in the drawing, even if each of the shift amounts Y3 and Y4 in the depth direction and each of the shift amounts X3 and X4 in the width direction of the green sheets 25e and 25f are both smaller than the radius of the side electrode, side edge electrode layers 41d, 41e, and 41f that must essentially be electrically connected are disconnected at a border between the neighboring side edge electrode layers 41e and 41f of the green sheets 25e and 25f, respectively, resulting in a laminated ceramic substrate with a disconnection defect.
FIG. 8(a) is a partial top view in the vicinity of a circular-shaped through hole 23 for a side electrode of a conventional green-sheet laminated body 26. Through holes 23m, 23n, and 23o for a side electrode each have the same shape. For example, green sheets 25m and 25o are shifted from a designed center in a side-electrode depth direction to the top in the drawing by Y5 smaller than the radius of the through hole for a side electrode with a green sheet 25n laminated thereon shifted from the designed center in the side-electrode depth direction to the bottom in the drawing by Y6 greater than the radius of the through hole for a side electrode. The green sheets 25m, 25n, and 25o are all disposed on the designed center in the side-electrode width direction. Depth direction centers 44m and 44o of the through holes 23m and 23o for a side electrode of the green sheets 25m and 25o are shifted from the designed center 45 in the side electrode-depth direction to the top in the drawing by the shift amount Y5. A depth direction center 44n of the through hole 23n for a side electrode of the green sheet 25n is also shifted from the designed center 45 in the side-electrode depth direction to the bottom in the drawing by the shift amount Y6.
FIG. 8(b) is a partial sectional view in the vicinity of a side electrode in which the green-sheet laminated body 26 is divided along a line 43c-43c (same as the designed center 43 in the side-electrode width direction). As seen in the drawing, the through holes 23m, 23n, and 23o for a side electrode that must essentially be electrically connected are disconnected at a border between the neighboring through holes 23m and 23n for a side electrode of the green sheets 25m and 25n, respectively, and at a border between the neighboring through holes 23n and 23o for a side electrode of the green sheets 25n and 25o, respectively. A side electrode of a green-sheet laminated body chip 27 obtained by dividing the green-sheet laminated body 26 along a line 45c-45c (same as the designed center 45 in the side-electrode depth direction) is to be disconnected, resulting in a laminated ceramic substrate with a disconnection defect.
As described above, there has been a problem that a disconnection defect caused by lamination shift may reduce production yield of a laminated ceramic substrate 20.
Accordingly, an object of the present invention is to provide a laminated ceramic substrate and a manufacturing method therefor in which occurrences of a disconnection defect of a laminated ceramic substrate 20 caused by green sheet lamination shift are reduced.